vss: Fix computation of extra slices.
[paraslash.git] / alsa_write.c
1 /*
2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file alsa_write.c paraslash's alsa output plugin */
8
9 /*
10 * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
11 * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
12 * based on the vplay program by Michael Beck.
13 */
14
15 #include <sys/types.h>
16 #include <dirent.h>
17 #include <alsa/asoundlib.h>
18
19 #include "para.h"
20 #include "fd.h"
21 #include "string.h"
22 #include "list.h"
23 #include "sched.h"
24 #include "ggo.h"
25 #include "write.h"
26 #include "alsa_write.cmdline.h"
27 #include "error.h"
28
29 /** always use 16 bit little endian */
30 #define FORMAT SND_PCM_FORMAT_S16_LE
31
32 /** Data specific to the alsa writer. */
33 struct private_alsa_write_data {
34 /** The alsa handle */
35 snd_pcm_t *handle;
36 /** Determined and set by alsa_open(). */
37 int bytes_per_frame;
38 /** The approximate maximum buffer duration in us. */
39 unsigned buffer_time;
40 /* Number of frames that fit into the buffer. */
41 unsigned buffer_frames;
42 /**
43 * The samplerate given by command line option or the decoder
44 * of the writer node group.
45 */
46 unsigned samplerate;
47 /**
48 * The number of channels, given by command line option or the
49 * decoder of the writer node group.
50 */
51 unsigned channels;
52 };
53
54 /* Install PCM software and hardware configuration. */
55 static int alsa_init(struct private_alsa_write_data *pad,
56 struct alsa_write_args_info *conf)
57 {
58 snd_pcm_hw_params_t *hwparams;
59 snd_pcm_sw_params_t *swparams;
60 snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
61 snd_pcm_uframes_t period_size;
62 int err;
63
64 err = snd_pcm_open(&pad->handle, conf->device_arg,
65 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
66 if (err < 0)
67 return -E_PCM_OPEN;
68
69 snd_pcm_hw_params_alloca(&hwparams);
70 snd_pcm_sw_params_alloca(&swparams);
71 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
72 return -E_BROKEN_CONF;
73 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
74 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
75 return -E_ACCESS_TYPE;
76 if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
77 return -E_SAMPLE_FORMAT;
78 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
79 pad->channels) < 0)
80 return -E_CHANNEL_COUNT;
81 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
82 &pad->samplerate, 0) < 0)
83 return -E_SET_RATE;
84 err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, 0);
85 if (err < 0 || !pad->buffer_time)
86 return -E_GET_BUFFER_TIME;
87 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
88 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
89 &pad->buffer_time, 0) < 0)
90 return -E_SET_BUFFER_TIME;
91 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
92 return -E_HW_PARAMS;
93 snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
94 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
95 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
96 period_size);
97 if (period_size == buffer_size)
98 return -E_BAD_PERIOD;
99 snd_pcm_sw_params_current(pad->handle, swparams);
100 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
101 if (buffer_size < 1)
102 start_threshold = 1;
103 else
104 start_threshold = PARA_MIN(buffer_size,
105 (snd_pcm_uframes_t)pad->samplerate);
106 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
107 start_threshold) < 0)
108 return -E_START_THRESHOLD;
109 stop_threshold = buffer_size;
110 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
111 stop_threshold) < 0)
112 return -E_STOP_THRESHOLD;
113 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
114 PARA_WARNING_LOG("unable to install sw params\n");
115 pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
116 * pad->channels / 8;
117 if (pad->bytes_per_frame <= 0)
118 return -E_PHYSICAL_WIDTH;
119 PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
120 if (snd_pcm_nonblock(pad->handle, 1))
121 PARA_ERROR_LOG("failed to set nonblock mode\n");
122 pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate;
123 PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames);
124 return 1;
125 }
126
127 /* Open an instance of the alsa writer. */
128 static int alsa_open(struct writer_node *wn)
129 {
130 struct alsa_write_args_info *conf = wn->conf;
131 struct writer_node_group *wng = wn->wng;
132 struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
133
134 wn->private_data = pad;
135 if (!conf->samplerate_given && wng->samplerate)
136 pad->samplerate = *wng->samplerate;
137 else
138 pad->samplerate = conf->samplerate_arg;
139 if (!conf->channels_given && wng->channels)
140 pad->channels = *wng->channels;
141 else
142 pad->channels = conf->channels_arg;
143 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
144 return 1;
145 }
146
147 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
148 {
149 struct private_alsa_write_data *pad = wn->private_data;
150 struct writer_node_group *wng = wn->wng;
151 struct timeval tv;
152 snd_pcm_sframes_t avail, underrun;
153
154 if (!pad->handle)
155 return 1;
156 if (*wng->loaded - wn->written < pad->bytes_per_frame)
157 return 1;
158 /*
159 * Data is available to be written to the alsa handle. Compute number
160 * of milliseconds until next buffer underrun would occur.
161 *
162 * snd_pcm_avail_update() updates the current available count of
163 * samples for writing. It is a light method to obtain current stream
164 * position, because it does not require the user <-> kernel context
165 * switch, but the value is less accurate, because ring buffer pointers
166 * are updated in kernel drivers only when an interrupt occurs.
167 */
168 avail = snd_pcm_avail_update(pad->handle);
169 if (avail < 0)
170 avail = 0;
171 underrun = (pad->buffer_frames - avail) * pad->buffer_time
172 / pad->buffer_frames / 1000;
173 if (underrun < 50)
174 underrun = 50;
175 underrun -= 50;
176 ms2tv(underrun, &tv);
177 if (tv_diff(&s->timeout, &tv, NULL) > 0)
178 s->timeout = tv;
179 return 1;
180 }
181
182 static int alsa_write_post_select(__a_unused struct sched *s,
183 struct writer_node *wn)
184 {
185 struct private_alsa_write_data *pad = wn->private_data;
186 struct writer_node_group *wng = wn->wng;
187 size_t bytes = *wng->loaded - wn->written;
188 unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
189 snd_pcm_sframes_t ret, frames, avail;
190
191 if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
192 wn->written = *wng->loaded;
193 return *wng->input_error;
194 }
195 if (!bytes) /* no data available */
196 return 0;
197 if (!pad->handle) {
198 int err = alsa_init(pad, wn->conf);
199 if (err < 0)
200 return err;
201 }
202 frames = bytes / pad->bytes_per_frame;
203 if (!frames) /* less than a single frame available */
204 return 0;
205 avail = snd_pcm_avail_update(pad->handle);
206 if (avail <= 0)
207 return 0;
208 frames = PARA_MIN(frames, avail);
209 ret = snd_pcm_writei(pad->handle, data, frames);
210 if (ret >= 0) {
211 wn->written += ret * pad->bytes_per_frame;
212 return 1;
213 }
214 PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
215 if (ret == -EPIPE) {
216 snd_pcm_prepare(pad->handle);
217 return 0;
218 }
219 if (ret == -EAGAIN)
220 return 0;
221 return -E_ALSA_WRITE;
222 }
223
224 static void alsa_close(struct writer_node *wn)
225 {
226 struct private_alsa_write_data *pad = wn->private_data;
227 PARA_INFO_LOG("closing writer node %p\n", wn);
228
229 if (pad->handle) {
230 snd_pcm_drain(pad->handle);
231 snd_pcm_close(pad->handle);
232 snd_config_update_free_global();
233 }
234 free(pad);
235 }
236
237 __malloc static void *alsa_parse_config(const char *options)
238 {
239 int ret;
240 struct alsa_write_args_info *conf
241 = para_calloc(sizeof(struct alsa_write_args_info));
242
243 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
244 ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
245 if (ret)
246 goto err_out;
247 PARA_INFO_LOG("help given: %d\n", conf->help_given);
248 return conf;
249 err_out:
250 free(conf);
251 return NULL;
252 }
253
254 /**
255 * the init function of the alsa writer
256 *
257 * \param w pointer to the writer to initialize
258 *
259 * \sa struct writer
260 */
261 void alsa_write_init(struct writer *w)
262 {
263 struct alsa_write_args_info dummy;
264
265 alsa_cmdline_parser_init(&dummy);
266 w->open = alsa_open;
267 w->close = alsa_close;
268 w->pre_select = alsa_write_pre_select;
269 w->post_select = alsa_write_post_select;
270 w->parse_config = alsa_parse_config;
271 w->shutdown = NULL; /* nothing to do */
272 w->help = (struct ggo_help) {
273 .short_help = alsa_write_args_info_help,
274 .detailed_help = alsa_write_args_info_detailed_help
275 };
276 alsa_cmdline_parser_free(&dummy);
277 }